Air vent and method of control thereof

ABSTRACT

Embodiments of the invention provide air conditioning system for use in a motor vehicle, the air conditioning system comprising a controller, at least one primary vent and an air delivery apparatus for location in a dashboard of a motor vehicle, the apparatus comprising: at least one secondary vent; and means for moving the at least one secondary vent between a retracted position in which the at least one secondary vent lies rearward of an A surface of the dashboard and a deployed position in which the at least one secondary vent is exposed for delivery of air to a zone of the vehicle, the controller being operable to: control the air conditioning system to provide a flow of air from the at least one primary vent while the air delivery apparatus is in a retracted position; and control the at least one vent to assume the deployed position responsive to a demand for a flow of air from the at least one secondary vent.

FIELD OF THE INVENTION

The present invention relates to an air vent for a motor vehicle and toa method of controlling an air vent. Aspects of the invention relate toan apparatus, to a controller, to a vehicle and to a method.

BACKGROUND

It is known to provide a heating, ventilation and air conditioning(HVAC) system in a motor vehicle although some motor vehicles are notprovided with air conditioning (AC) functionality.

Known motor vehicle ventilation systems are operable to provide a flowof air into a cabin of the vehicle. Air may be delivered to one or moreof a front footwell zone, a front facial zone (to one or more front seatoccupants) and a front windscreen zone. The facial zone is typicallyserviced by a pair of side vents and a pair of centre air vents. Theside vents are located at opposite (left and right) extremes of aninstrument panel or dashboard of the vehicle whilst the centre vents arelocated in a central area of the panel. The instrument panel may also bereferred to as a fascia.

One or more controls are typically provided for controlling the relativeamounts of air that flow through the vents associated with each zone.Furthermore, the vents serving the facial zone may be operable to adjusta direction in which air flows from the vents into the facial zone.

SUMMARY

According to one aspect of the invention there is provided an airconditioning system for use in a motor vehicle, the air conditioningsystem comprising a controller, at least one primary vent and an airdelivery apparatus for location in a dashboard of the motor vehicle, theapparatus comprising:

-   -   at least one secondary vent; and    -   means for moving the at least one secondary vent between a        retracted position in which the at least one secondary vent lies        rearward of an A surface of the dashboard and a deployed        position in which the at least one secondary vent is exposed for        delivery of air to a zone of the vehicle,    -   the controller being operable to:    -   control the air conditioning system to provide a flow of air        from the at least one primary vent while the air delivery        apparatus is in a retracted position; and    -   control the at least one vent to assume the deployed position        responsive to a demand for a flow of air from the at least one        secondary vent.

In this way the invention provides an air conditioning system in which aprimary vent can provide air flow with or without a secondary vent. Thesecondary vent can be moved into a deployed position and provide airflow when required.

In describing the position of the secondary vent, the word rearward isnot a reference to the direction of facing of the vehicle, but only ofthe direction of facing of the A surface. As such, when in a retractedposition, the secondary vent may lie forward of an A surface withrespect to the vehicle. The at least one secondary vent may lie belowthe A surface of the dashboard while in the retracted position. Asurface of the at least one secondary vent may lie substantially flushwith the A surface of the dashboard while in the retracted position.

It may be that the at least one primary vent is a fixed vent.

By A surface is meant a surface of the dashboard that is visible to auser in normal use, i.e. the surface that is exposed to the interiorcabin environment of the vehicle. An A surface of the dashboard may forexample be provided by a trim panel. Thus reference to an A surface ofthe dashboard may also be considered to be reference to an outer surfaceof the dashboard.

It is to be understood that reference to moving the at least onesecondary vent includes movement by translation with no rotation of theat least one vent, rotation with no translation and movement in whichthe at least one vent is subject to both rotation and translation.

Advantageously the deployed position is a position in which the at leastone secondary vent lies forward of the A surface.

By forward is included above the A surface, i.e. above and not behindthe outer surface of the dashboard.

The apparatus may be arranged to be concealed behind the dashboard whenin the retracted condition.

The apparatus may comprise a cover portion, the cover portion providinga portion of the A surface of the dashboard, the cover portion beingarranged to move with the at least one vent.

Advantageously in the retracted position of the at least one secondaryvent the cover portion at least partially conceals the apparatus.

Further advantageously in the retracted position of the at least onesecondary vent the cover portion conceals the apparatus substantiallyentirely.

Optionally the cover portion is coupled to a portion of the apparatus.

Advantageously the cover portion comprises a trim panel.

Alternatively the cover portion is integrally formed with the apparatus.

The means for moving the at least one secondary vent may comprise apivot arrangement.

The apparatus may comprise a vent carrier member arranged to bear the atleast one secondary vent, the carrier member being hingedly coupled to avent substrate member, the substrate member being arranged to be coupledto a portion of the motor vehicle.

Advantageously the means for moving the at least one secondary ventcomprises an actuator, the apparatus comprising clutch means arranged toallow the secondary vent to swing from the deployed position to theretracted position responsive to application of pressure to theapparatus without requiring actuation of the actuator.

This feature has the advantage that damage to the apparatus may beprevented in the event a load is placed on the apparatus that mightotherwise cause damage.

Further advantageously the apparatus comprises switch means operable bya user to cause the at least one secondary vent to assume the retractedcondition.

This feature has the advantage that the user may force retraction of theat least one secondary vent following deployment thereof.

The switch means may be operable by application of downward pressure onthe apparatus.

Thus if a user may conveniently retract the at least one secondary ventwhen required. This feature has the advantage that if the user places anobject on the apparatus that is sufficiently heavy to actuate the switchthe apparatus will close. Thus the apparatus anticipates that a user mayfind it more convenient if the at least one vent were closed.

The controller may be operable to control the apparatus to remain in thedeployed condition when air is no longer required to be deliveredthrough the at least one secondary vent responsive to a value of atleast one selected from an outside air temperature and a solar load onthe vehicle.

This feature has the advantage that apparatus may be controlled in sucha manner that the likelihood the apparatus is switched between retractedand deployed conditions repeatedly during the course of a journey may bereduced.

Thus if the controller determines that the vehicle is subject to arelatively high thermal load, for example due to a high ambient airtemperature or a high solar load the controller may determine that theapparatus should remain in the deployed condition since it is likely theapparatus will be required to deliver cooled air to the vehicle cabinagain within a relatively short time period.

If the controller determines the outside air temperature is relativelylow and the solar load is low the vehicle may be configured to determinethat the apparatus may be required to deliver heated air to the cabinwithin a relatively short time period and therefore maintain theapparatus in the deployed condition.

The controller may be operable to control the apparatus to remain in thedeployed condition when air is no longer required to be deliveredthrough the at least one vent responsive to a value of an average flowrate of air through the at least one vent since the apparatus wasdeployed.

The controller may be operable to control the apparatus to switchbetween retracted and deployed conditions responsive to a value ofrequired flow rate of air to a facial zone of the cabin.

Advantageously the apparatus is configured to provide a flow of air tothe facial zone of the cabin when a required flow rate of air exceedsthat which can be provided through a primary vent operable to deliverair to the facial zone.

The primary vents may include for example one or more side vents andoptionally one or more screen vents.

Thus if the one or more primary vents are unable to deliver a requiredflow of air to the facial zone the controller may be arranged to controlthe apparatus to deliver a required flow of air to the facial zone.

In a still further aspect of the invention there is provided a motorvehicle comprising a system according to another aspect of theinvention.

The apparatus is advantageously coupled to a dashboard of the motorvehicle.

According to a further aspect of the invention there is provided amethod of delivering air to a cabin of a motor vehicle, the methodcomprising:

-   -   providing a controller, at least one primary vent and at least        one secondary vent;    -   controlling the at least one primary vent to provide a flow of        air while the air delivery apparatus is in a retracted position        in which the at least one secondary vent lies rearward of an A        surface of a dashboard of the vehicle; and    -   moving the at least one secondary vent between a retracted        position and a deployed position in which the at least one        secondary vent is exposed for delivery of air to a zone of the        vehicle, responsive to a demand from the controller for a flow        of air from the at least one secondary vent.

The at least one secondary vent may lie below the A surface of thedashboard while in the retracted position. A surface of the at least onesecondary vent may lie substantially flush with the A surface of thedashboard while in the retracted position.

It may be that the at least one primary vent is a fixed vent.

Within the scope of this application it is envisaged that the variousaspects, embodiments, examples, features and alternatives set out in thepreceding paragraphs, in the claims and/or in the following descriptionand drawings may be taken independently or in any combination thereof.For example, features described in connection with one embodiment areapplicable to all embodiments, except where there is incompatibility offeatures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying figures in which:

FIG. 1 is a perspective view of apparatus according to an embodiment ofthe present invention in a deployed condition;

FIG. 2 is a perspective view of the apparatus of FIG. 1 in a retractedcondition;

FIG. 3 is a perspective view of the apparatus of FIG. 1 from above;

FIG. 4 is a front view of the apparatus of FIG. 1 in the deployedcondition;

FIG. 5 is a perspective view of the apparatus of FIG. 1 installed in adashboard of a motor vehicle in the deployed condition;

FIG. 6 is a perspective view of the apparatus of FIG. 1 installed in adashboard of a motor vehicle in the retracted condition;

FIG. 7 is a plan view of a motor vehicle having the active ventapparatus of FIG. 1 installed therein; and

FIG. 8 illustrates schematically (a) a relationship between an Sparameter and a selected HVAC system mode of the vehicle and (b) arelationship between the selected HVAC system mode and the condition ofthe active vent apparatus.

DETAILED DESCRIPTION

FIG. 1 shows active vent apparatus 100 according to an embodiment of thepresent invention. The apparatus 100 has a pair of air vents 110operable to deliver air into a cabin of a motor vehicle 1. A left airvent 110L is arranged to direct air to a left front seat occupant of thevehicle 1 whilst a right air vent 110R is arranged to direct air to aright front seat occupant.

The vents 110 are supported by a vent carrier 130C. The vent carrier130C is in the form of a panel having the vents 110 coupled thereto atone end. At the opposite end the carrier 130C is coupled to ventsubstrate 130S by means of a pivot hinge 130P.

The vent substrate 130C is arranged to be fixedly coupled to a portionof a dashboard 5 of the vehicle 1 as shown in FIG. 2 (not shown in FIG.1 for clarity). Thus the vent carrier 130C is operable to swing awayfrom or towards the dashboard 5 about the pivot hinge 130P. Theapparatus is shown in FIG. 1 in a deployed condition in which the ventcarrier 130C is at an extreme of swing away from the vent substrate130S. FIG. 2 is a corresponding image showing the apparatus 100 in aretracted condition in which the vent carrier 130C is at an extreme ofswing towards the vent substrate 130S.

The vent substrate 130S has a lower air conduit 141 coupled thereto, thelower air conduit 141 having a basal portion 141B that is arranged to becoupled to a heating, ventilation and air conditioning (HVAC) unit 50 ofthe vehicle 1. The HVAC unit 50 is arrange to deliver a flow of air tothe apparatus 110 when required.

The lower air conduit 141 is arranged to direct air entering the conduit141 to an inlet of each of a pair of upper air conduits 132L, 132R (FIG.3) that are coupled to the vent carrier 130C. The upper conduits 132L,132R are coupled to the left and right air vents 110L, 110R respectivelyand arranged to direct air therethrough.

Since the vent carrier 130C is pivotably movable with respect to thevent substrate 130S, the upper air conduits 132L, 132R are coupled to amanifold 132M defining a skirt around the lower air conduit 141. As thevent carrier 130C pivots towards and away from the vent substrate 130Sabout the pivot hinge 130P, the manifold 132M moves alternatelydownwardly and upwardly around the lower air conduit 141.

In the arrangement shown the manifold 132M is arranged to form a sealaround the lower air conduit 141 when the apparatus 100 is in thedeployed condition. In some embodiments the manifold 132M is arranged toform a seal around the lower air conduit 141 when the apparatus 100 isin the deployed or retracted condition. In some embodiments the manifold132M is arranged to form a seal around the lower air conduit 141 whenthe apparatus is in the deployed or retracted condition and forsubstantially all positions of the manifold 132M between the deployedand retracted conditions.

The vent carrier 130C is arranged to be swung between the retracted anddeployed positions by a lift mechanism 160 driven by an actuator such asa stepper motor 162.

The stepper motor 162 is arranged to rotate a drive bar 163 that isoriented parallel to the pivot hinge 130P but at a forward end of thevent substrate 130S opposite that at which the pivot hinge 130P islocated. The drive bar 163 lies in a lateral orientation across a widthof the apparatus 100. Left and right lower lift arms 165L, 165R arefixedly coupled to the drive bar 163 at opposite ends thereof, one belowthe left vent 110L and one below the right vent 110R. Thus the lowerlift arms 165L, 165R are arranged to rotate with the drive bar 163.

The lower lift arms 165L, 165R are each coupled by means of a respectivehinge pivot 166 to left and right upper lift arms 167L, 167R,respectively. The upper lift arms 167L, 167R are in turn coupled torespective locations of the vent carrier 130C by means of furtherrespective pivot hinges 168.

It is to be understood that rotation of the drive bar 163 about alongitudinal axis thereof causes rotation of the lower lift arms 165L,165R with the drive bar 163. This causes the upper lift arms 167L, 167Rto rotate about pivot hinges 166 and in turn pivot hinges 168. Thus byrotation of the drive bar 163 in alternate opposite directions the ventcarrier 130C may be moved between the retracted and deployed conditionsas required.

In some embodiments the lift mechanism 160 may provide an over centrecam arrangement.

In the embodiment shown the apparatus 100 is arranged whereby ifsufficient force is placed on the vent carrier 130C when the carrier130C is in the deployed position, a clutch mechanism 159 allows thecarrier 130C to swing towards the retracted position. This feature hasthe advantage that if an unexpectedly high force is applied to the ventcarrier 130C in a downward direction, for example if a sufficientlyheavy weight is placed on the carrier 130C, the carrier 130C will movetowards the retracted condition preventing damage to the lift mechanism160.

If the carrier 130C is unable to open when the stepper motor 162 isactuated, the clutch mechanism 159 similarly allows slip of the motor162 to prevent damage to the lift mechanism 160.

A pair of damper elements 151L, 151R are provided for damping vibrationof the apparatus 100 and assisting smooth movement of the vent carrier130C between the retracted and deployed positions. The elements 151L,151R are provided on respective left and right sides of the apparatus100 and are in the form of a pair of lever arms hingedly coupledtogether by means of a resilient hinge arrangement. Respective leverarms of each element 151L, 151R are arranged to abut facing portions ofthe vent substrate 130S and vent carrier 130C to urge the substrate 130Sand carrier 130C away from one another, i.e. to urge the apparatus 100towards the deployed condition. In the embodiment shown the elements151L, 151R are each formed from a single length of wire, having acentral portion wound into the form of a coil spring.

The air vents 110 themselves are provided with respective sets ofpivotable louvre slats 112, 114. A first set of slats 112 are pivotableabout a substantially horizontal axis and allow the occupant to controlan angle of elevation of airflow from respective vents 110. A second setof slats 114 behind the first set 112 allow the occupant to control alateral (left/right) direction of airflow from the vent 110. Therespective sets of slats 112, 114 are movable by means of wheels 115(slats 112) and slide controls or levers 113 (slats 114). The levers 113are slidably coupled to a central slat 112C of the first set of slatsalong which they may be slid in order to effect rotation of the secondset of slats 114.

The vent substrate 130S is provided with an aperture 131S therethroughto which an audio speaker may be mounted. This feature allows thedistance between the pivot hinge 130P and air vents 110 to be maderelatively large without requiring relocation of the speaker. Acorresponding aperture 131C in the vent carrier 130C allows sound fromthe speaker to pass therethrough with reduced attenuation. A speakergrille may be coupled to the carrier 130C to cover the aperture 131C. Insome embodiments the speaker may be coupled to the carrier 130C insteadof the substrate 130S.

It can be seen from FIG. 1 that the vent carrier 130C is constructed soas to define a relatively large lever arm between the hinge pivot 130Pand vents 110. This feature has the effect of reducing an angle throughwhich the air vents 110 must rotate about pivot hinge 130P when theapparatus 100 moves between the retracted and deployed conditions. It isto be understood that pivot hinge 130P is arranged to lie parallel to alateral axis of the vehicle 1. The reduction in angle through which theair vents 110 must rotate can enhance an enjoyment by an occupant of thevehicle 1 of the theatre of air vent 110 deployment and retraction.

Furthermore, this feature can enhance an aesthetic appeal of theapparatus 100 when in the deployed condition since relatively abruptchanges in a shape of the dashboard rearward of the apparatus 110 (asviewed by a vehicle occupant) may be eliminated in some embodiments,such as that of FIG. 5.

FIG. 5 shows the apparatus installed in a central region of a dashboard5 of a motor vehicle 1, the apparatus 100 being in the deployedcondition in the configuration of FIG. 5. Because the vents 110 arepositioned centrally of the dashboard the vents 110 may also be referredto as centre vents 110.

The vents 110 are provided with upright side trim panels 117 along theirouter sides. A cover trim panel 180 is coupled to the vent carrier 130Cto conceal the carrier 130C and other portions of the apparatus 100except for the vents 110 and side trim panels 117 when in the deployedconfiguration. In the example shown, the cover trim panel 180 is coveredwith materials complementary to those used in the surrounding instrumentpanel or dashboard 5 so as to enhance the overall appearance of thevehicle interior.

FIG. 6 is a corresponding view of the dashboard 5 with the apparatus 100in the retracted condition. It can be seen that when in the retractedcondition the apparatus 100 is completely concealed except for the covertrim panel 180.

The apparatus 100 is positioned such that when in the deployed conditionthe apparatus 100 may deliver a flow of air to a front upper body (orfacial) zone of the vehicle 1.

FIG. 7 is a schematic plan view of the vehicle 1 showing the location offurther vents of the vehicle 1.

The dashboard 5 has a pair of side vents 10L, 1OR arranged to provideair to front side facial zones of the vehicle 1, the side vents 10L, 1ORbeing located in the dashboard 5 on respective opposite sides of thevehicle 1. In the embodiment of FIG. 7 the side vents 10L, 10R are notretractable but are permanently deployed. In some embodiments the sidevents 10L, 1OR may also be retractable. A pair of foot vents 15L, 15Rare provided below the dashboard 5 in respective left and rightfootwells 15WL, 15WR of the vehicle 1, the foot vents 15L, 15R beingoperable to deliver a flow of air to a front foot zone of the vehicle 1.A pair of screen vents 20L, 20R are operable to deliver a flow of air torespective left and right portions of a windscreen of the vehicle 1.

The apparatus 100 is arranged to be controlled by means of an HVACcontroller 40. The controller 40 is arranged to control the apparatus100 to assume the retracted or deployed conditions and to control a flowrate of air through the vents 110 when the apparatus 100 is in thedeployed condition.

The HVAC controller 40 is operable to deliver a flow of air through thescreen vents 20L, 20R alone, the foot vents 15L, 15R alone, through thefoot vents 15L, 15R and the side vents 10L, 10R simultaneously and notthrough the centre vents 110, through the foot vents 15L, 15R, sidevents 10L, 10R and centre vents 110 simultaneously or through side vents10L, 10R and centre vents 110. Other arrangements are also useful.

If the apparatus 100 is in the retracted condition and the controller 40determines that airflow is required to the facial zone of the vehicle 1,the controller 40 maintains the apparatus 100 in the retracted conditionif the required ratio of airflow between the facial zone and foot zoneis below a prescribed value. The controller 40 bleeds air through theside vents 10L, 10R in order to deliver the required flow to the facialzone.

However if the required ratio exceeds the prescribed value thecontroller 40 controls the apparatus 100 to assume the deployedcondition and opens a valve between the HVAC unit 50 and the lower airconduit 141 in order to allow airflow through the apparatus 100. In someembodiments, in order to prevent unwanted NVH (noise, vibration andharshness) such as whistling, the controller 40 may be arranged tocontrol the apparatus to assume the deployed condition before allowingair to enter the lower conduit 141.

It is to be understood that an aim of some embodiments is to reduce thenumber of times the apparatus 100 is required to move between theretracted and deployed conditions during the course of a journey. Asdescribed above, one way of accomplishing this is by bleeding airthrough the side vents 10L, 10R to provide air flow to the front facialzone when relatively low flow rates of air are to be delivered to thefacial zone.

In some embodiments the controller 40 is operable to balance airflowbetween the side vents 10L, 10R and the screen vents 20L, 20R as analternative to controlling the apparatus 100 to assume the deployedcondition as the amount of air to be delivered to the facial zoneincreases. Once the required flow rate of air to the facial zone exceedsan amount that is to be delivered through the side and screen vents theapparatus 100 may be controlled to assume the deployed condition.

A further method of reducing movement is to implement a hysteresis inrespect of when the controller 40 changes the ratio of airflow betweenthe facial and foot zones.

The controller 40 is configured to determine a value of a parameter Sresponsive to which the controller 40 determines the relativedistribution of airflow between the screen, facial zone and foot zone ofthe vehicle 1. The controller 40 also determines whether the active ventapparatus 100 should assume the retracted or deployed conditionsresponsive to the value of S.

FIG. 8(a) lists eight discrete modes the HVAC controller 40 may controlthe vehicle to assume in respect of airflow delivery. The modes are:

-   -   1. Face mode (airflow only to the facial zone of the vehicle);    -   2. Face/foot mode B/L 1 (airflow primarily to the facial zone        with bleed flow to the foot zone);    -   3. Face/foot mode B/L 2 (airflow primarily to the facial zone        with more air flow to the foot zone than B/L 1, the ratio of        airflow rates to the facial/foot zones being lower than that of        mode 2, i.e. more airflow is provided to the foot zone relative        to that to the facial zone when in mode 3);    -   4. Face/foot mode B/L 3 (airflow to the facial and foot zones,        the ratio of airflow rates to the facial/foot zones being lower        than that of mode 3);    -   5. Face/foot mode B/L 4 (airflow to the facial and foot zones,        the ratio of airflow rates to the facial/foot zones being lower        than that of mode 4);    -   6. Face/foot mode B/L 5 (airflow primarily to the foot zone, the        ratio of airflow rates to the facial/foot zones being lower than        that of mode 5);    -   7. Face/foot mode B/L 6 (airflow primarily to the foot zone with        bleed airflow to the facial zone, the ratio of airflow rates to        the facial/foot zones being lower than that of mode 6); and    -   8. Foot mode (airflow only to the foot zone of the vehicle).

The abbreviation B/L refers to bi-level flow.

The values shown in columns AD and AO of FIG. 8(a) refer to thepositions of respective valve actuators, for example position values ofrespective stepper motors. Actuator AD is a defrost actuator arranged tocontrol the position of a valve operable to control flow of air throughscreen vents 20L, 20R. Actuator AO is arranged to control the positionof a valve operable to determine the ratio of airflow rates between thefoot and facial zones.

The controller 40 is arranged whereby if the controller 40 hascontrolled the vehicle to assume mode 6 or higher, the active ventapparatus 100 assumes the retracted condition. This condition may bereferred to as a ‘centre vent closed’ (CVC) condition as shown in FIG.8(b). If the controller 40 subsequently controls the HVAC system toassume mode 5, the controller 40 controls the active vent apparatus 100to assume the deployed condition. This condition may be referred to as a‘centre vent open’ (CVO) condition. This transition is illustrated inFIG. 8(b).

If the controller subsequently controls the HVAC system to assume mode6, the controller controls the active vent apparatus to assume the CVCcondition.

The controller 40 is configured to compute a value of a parameter Sresponsive to one or more vehicle cabin temperatures and a solar load onthe vehicle 1. The controller 40 controls the HVAC system to assume oneof modes 1 to 8 responsive to the value of S.

FIG. 8(a) illustrates the relationship between the value of theparameter S and the mode assumed by the HVAC system. It can be seen thatthe controller 40 implements hysteresis functionality in respect oftransitions between modes responsive to the value of S. That is, athreshold value of S for a transition from a first mode to the nexthigher mode is greater than the threshold value for a transition fromthat next higher mode back to the first mode. Similarly, the thresholdvalue of S for a transition from a first mode to the next lower mode islower than the threshold value for a transition from that next lowermode back to the first mode.

By way of example and by reference to FIG. 8(a), suppose the controller40 determines the value of S to be 0.48. It can be seen that this valuecorresponds to position P1 of the mode map shown on the right hand sideof FIG. 8(a). This value may be seen to correspond to mode 5 (left handportion of the table) as indicated by the arrowheads superimposed on thefigure. For the avoidance of doubt it is stated that values of S recitedherein are calibratable depending on a given system configuration.

It can be seen that in mode 5, the actuator AD is controlled to assumeposition 280 and actuator AO is controlled to assume position 628.

If the value of S falls, the solid line passing through S=0.48 remainsat a level corresponding to mode 5 until the value of S falls below0.46, when the line falls to a level indicating mode 4 should beassumed. In mode 4 actuator AD is controlled to assume position 20 andactuator AO is controlled to assume position 705.

If the value of S subsequently rises above 0.46, it can be seen thatthis solid line remains at a level corresponding to mode 4 until S risesabove 0.50, when the line transitions to a level corresponding to mode5.

Thus the controller 40 is configured to reduce a risk that mode chatteroccurs, i.e. the HVAC system is controlled to fluctuate repeatedlybetween modes in rapid succession. This has the advantage that driverirritation and potential distraction in respect of deployment andretraction of the active vent apparatus 100 may be reduced.

In some embodiments the controller 40 is configured to respondrelatively quickly to a demand for air flow to a facial zone of thevehicle 1, controlling the apparatus 100 to assume the CVO conditionrelatively quickly in response to airflow demand. However the controller40 may be configured to retain the apparatus in the CVO condition oncethe value of S has risen to a value at which airflow through theapparatus 100 is no longer required. The HVAC system may therefore becontrolled to terminate flow of air through the apparatus 100 but toretain the apparatus in the CVO condition. This has the advantage that arisk that the apparatus 100 transitions between CVC and CVO conditionsrepeatedly is reduced as noted above.

In some embodiments the apparatus 100 may be configured to allow bleedairflow therethrough even when in the retracted condition, CVC. Forexample, the cover 180 may be provided with a vent, for example alow-visibility vent and/or perforations to allow bleed airflowtherethrough. When a greater airflow is required than may be achieved bybleed flow the controller 40 may be configured to control the apparatus100 to assume the CVO condition.

Embodiments of the invention have the advantage that a dashboard 5 of amotor vehicle may be fabricated with enhanced aesthetic appeal. This isbecause when a user first enters the vehicle 1 when the HVAC system isturned off, the active air vent apparatus will be hidden since it willtypically be in the retracted condition. Only when flow of air throughthe centre vents 110 is required in order to meet cabin comfortrequirements will the vents 100 become visible. The theatre associatedwith vent apparatus 100 opening and closing can also enhance driverenjoyment of the vehicle 1.

It is to be understood that a user interface, which may be via a visualdisplay screen such as a touchscreen, may allow a user to customise oneor more functions of the controller 40. For example, the controller 40may be operable to control the active vent apparatus 100 to assume thedeployed condition whenever an engine of the vehicle is switched on, orwhenever the vehicle 1 is powered up even if the engine is not on. Insome embodiments the controller 40 may be operable to control theapparatus 100 to assume the deployed condition whenever the HVAC systemis activated. Other arrangements are also useful.

In some embodiments the apparatus 100 includes control means in the formof a switch 180 by means of which a user may over-ride deployment of theapparatus by pressing downwards on the cover trim panel 180. Thus if theuser requires the apparatus 100 to assume the retracted condition theuser may simply press downwardly on the panel 180, the apparatus 100being controlled automatically to assume the retracted conditionresponsive to actuation of the switch.

Throughout the description and claims of this specification, the words“comprise” and “contain” and variations of the words, for example“comprising” and “comprises”, means “including but not limited to”, andis not intended to (and does not) exclude other moieties, additives,components, integers or steps.

Throughout the description and claims of this specification, thesingular encompasses the plural unless the context otherwise requires.In particular, where the indefinite article is used, the specificationis to be understood as contemplating plurality as well as singularity,unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties orgroups described in conjunction with a particular aspect, embodiment orexample of the invention are to be understood to be applicable to anyother aspect, embodiment or example described herein unless incompatibletherewith.

1. A controller for use in an air conditioning system for a motorvehicle, the controller being configured to: control the airconditioning system to provide a flow of air from at least one primaryvent in dependence on a required flow rate of air; and, in response tothe required flow rate of air exceeding a predetermined flow rate, tocontrol the at least one secondary vent to assume a deployed positionand to provide a flow of air from the at least one primary vent and theat least one secondary vent in the deployed position.
 2. A controller asclaimed in claim 1, wherein, in response to activation of a useroperable switch, the controller is configured to over-ride deployment ofat least one secondary vent and to control the at least one secondaryvent to assume the retracted condition.
 3. A controller as claimed inclaim 2, wherein activation of the user operable switch comprises theapplication of downward pressure to the at least one secondary vent. 4.A controller as claimed in claim 1, wherein the controller is operableto control the at least one secondary vent to remain in the deployedcondition when air is no longer required to be delivered through the atleast one secondary vent responsive to a value of at least one selectedfrom an outside air temperature and a solar load on the vehicle.
 5. Acontroller as claimed in claim 1, wherein the controller is operable tocontrol the at least one secondary vent to assume the retracted positionin response to the required flow rate dropping below a threshold value.6. A controller as claimed in claim 5, wherein the threshold value islower than the predetermined flow rate.
 7. A controller as claimed inclaim 1, wherein the controller is configured to control the at leastone secondary vent to transition between the deployed and retractedconditions using a hysteresis functionality.
 8. A controller as claimedin claim 1, wherein the controller is operable to control the at leastone secondary vent to remain in the deployed condition when air is nolonger required to be delivered through the at least one secondary ventresponsive to a value of an average flow rate of air through the atleast one secondary vent since the at least one secondary vent wasdeployed.
 9. A controller as claimed in claim 1, wherein a predeterminedflow rate is a predetermined flow rate of air required to be provided toa facial zone of a cabin of the vehicle.
 10. A controller as claimed inclaim 1, wherein the controller is operable to open a valve to allow airto flow through the at least one secondary vent only after the at leastone secondary vent has assumed the deployed condition.
 11. An airconditioning system for a motor vehicle comprising a controller asclaimed in claim
 1. 12. A motor vehicle comprising a controller asclaimed in claim
 1. 13. An apparatus for an air conditioning system fora motor vehicle comprising a vent pivotable between a retracted positionand a deployed position in which the vent is arranged to provide a flowof air to the cabin of the vehicle; a lift mechanism for moving the ventfrom the retracted position to the deployed position; an actuator fordriving the lift mechanism; and a clutch mechanism arranged to allow thevent to move from the deployed position to the retracted position,responsive to application of pressure to the apparatus, withoutrequiring actuation of the actuator.
 14. An apparatus as claimed inclaim 13, wherein the apparatus comprises a rotatable drive bar that isoriented parallel to a pivot hinge of the apparatus.
 15. An apparatus asclaimed in claim 14, wherein the drive bar is located at a forward endof a vent substrate opposite that at which the pivot hinge is located.16. An apparatus as claimed in claim 13, wherein the actuator is astepper motor.
 17. An apparatus as claimed in claim 13, wherein theclutch mechanism is configured to allow slip of the actuator if the ventis unable to move from the retracted position to the deployed position.18. An apparatus as claimed in claim 13, wherein the lift mechanismcomprises a damper element configured to enable smooth movement of thevent between the retracted and deployed positions.